Can one of the co executor's distribute property without the other co executor?

Generally, no. First of all, when questions arise involving a will, you first see if the will makes a specific provision for the problem. A will may state that each executor may act independently of the other but this can cause problems. If the will is silent regarding independent action then look to the law of the jurisdiction in which the will was probated. Most state's law provide that unless the will says otherwise, the executors must act together. When there are two co-executors and they disagree about distribution, the matter could wind up in court where it will determine who is right and who is wrong.